8. CONCLUSION

The preceding discussion of the spectral class-form relationship
seems to apply to approximately 80 percent of the brighter
extragalactic systems; if those in the highest luminosity category
are considered, the percentage is probably greater. Among
well-known systems, the most striking exception is probably NGC 205
- one of the fainter companions of the Andromeda Nebula. In
spite of its amorphous elliptical structure, its spectral type is
considerably earlier than in the K-systems; the principal contributors
to the integrated light in the photographic region are probably
F-type stars. It is of considerably lower luminosity, however, than
the giant ellipticals and spirals, and Baade has pointed out the
presence of several dust clouds and a number of blue stars.
8 Also,
Baum and Schwarzschild found the anomaly that nebular patches
near NGC 205 and near M 31 have the same color, despite a
presumed membership in two different stellar populations.
9

This investigation was begun while one of us (W.W.M.) was
an Alexander F. Morrison Research Associate at the Lick
Observatory, and was continued while he was Visiting Professor at
the California Institute of Technology. He wishes to make grateful
acknowledgment for facilities and plate material made available
by Directors I. S. Bowen of the Mount Wilson and Palomar
Observatories and C. D. Shane of the Lick Observatory. He is
also indebted to Dr. G. H. Herbig for help in obtaining Crossley
spectrograms of M 31, and to Drs. W. Baade and A. R. Sandage
for discussions on the subject of classification of galaxies. The
research was supported in part by a grant (to W.W.M.) by the
Office of Naval Research.